Telecommunication system for selecting optimum transfer rate

Abstract

A telecommunication method and equipment in a network in which at least two exchange units are connected between an originating data terminal and a terminating data terminal. A transfer rate selection unit is provided in each exchange unit, for selecting one rate arbitrarily from a plurality of transfer rates. An originating call is accessed by including a plurality of accessible transfer rates in a call setup message from the originating data terminal, and each transfer rate is determined in the transfer rate selection units in the exchange units in view of a free channel in a trunk line, from received transfer rate information. The call setup information is transferred to the terminating data terminal, and is modified, based on the transfer rate data included in the call connect message from the terminating data terminal in response to the call setup message by the transfer rate selection unit in each exchange unit. The originating data terminal is informed of the data, and communication therewith is ultimately established by using the efficient transfer rate.

I claim: 
     
       1. A telecommunication method in a network in which at least two exchange units are to be connected between an originating data terminal and a terminating data terminal which communicate over an interexchange unit circuit switched connection established by sending a call setup message from an originating exchange unit to a terminating exchange unit, and sending a call connect message from said terminating exchange unit to said originating exchange unit in response to said call setup message in a signalling channel; the method comprising the steps of: providing a transfer rate selection unit within each of said exchange units,   determining a plurality of available transfer rates within free channels in a trunk line to said terminating exchange unit, by the transfer rate selection unit within said originating exchange unit,   sending information about said plurality of available transfer rates included in said call setup message from said originating exchange unit, to said terminating exchange unit,   selecting a transfer rate information actually to be used in said circuit switched connection between said originating exchange unit and said terminating exchange unit from said information about a plurality of available transfer rates, by the transfer rate selection unit within said terminating exchange unit,   sending a selected transfer rate information, included in said call connect message from said terminating exchange unit to said originating exchange unit,   changing said available transfer rate provisionally determined by said transfer rate selection means within said originating exchange unit, to said selected transfer rate included in said call connect message,   establishing said circuit switched connection, in accordance with said selected transfer rate between said exchange units to provide communication therebetween.   
     
     
       2. A telecommunication method according to claim 1, wherein a transit exchange unit is provided, which transit exchange unit is connected between said originating exchange unit and said terminating exchange unit; said method further comprising the steps of: providing a transfer rate selection unit within said transit exchange unit,   receiving said information about a plurality of available transfer rates by said transfer rate selection unit within said transit exchange unit, said information being included in said call setup message from said originating exchange unit to said transit exchange unit,   checking in said transit exchange unit whether or not each of said plurality of available transfer rates is available to transfer, within free channels in a trunk line to said terminating exchange unit,   sending modified information about a plurality of available transfer rates, included in said call setup message from said transit exchange unit to said terminating exchange unit,   receiving said selected transfer rate information by said transfer rate selection unit within said transit exchange unit, included in said call connect message from said terminating exchange unit to said transit exchange unit,   establishing said circuit switched connection in accordance with said selected transfer rate information, between said transit exchange unit and said terminating exchange unit to provide communication therebetween,   sending said a selected transfer rate information, included in said call connect message from said transit exchange unit to said originating exchange unit, and   establishing said circuit switched connection, in accordance with said selected transfer rate information, between said originating exchange unit and said transit exchange unit.   
     
     
       3. A telecommunication method according to claim 1, wherein said originating exchange unit and said terminating exchange unit are connected by a trunk line in accordance with the integrated services digital network (ISDN) specification; said method further comprising the steps of: sending said information about a plurality of available transfer rates within an extended information element which users can determine freely in addition to standardized transfer rate information within a standardized information element, from said originating exchange unit to said terminating exchange unit, said information elements being included in a standardized call setup message,   selecting a transfer rate information actually to be used from said information about a plurality of available transfer rates if said information about said plurality of available transfer rates is received within said extended information element, or, considering said standardized transfer rate information as said selected transfer rate information if said extended information element is not received or is invalid, by said transfer rate selection unit within said terminating exchange unit,   sending said selected transfer rate information within said extended information element included in a standardized call connect message from said terminating exchange unit to said originating exchange unit, and   establishing an integrated services digital network (ISDN) circuit switched connection between said exchange units in accordance with said selected transfer rate information if it is included in said standardized call connect message, or, in accordance with said standardized transfer rate information included in said standardized call setup message if said extended information element is absent or is invalid in said standardized call connect message, to provide communication between said exchange units.   
     
     
       4. A telecommunication method according to claim 3, wherein a transit exchange unit is provided and said originating, transit and terminating exchange units are connected to each other by a trunk line in accordance with the integrated services digital network (ISDN) specification; said method further comprising the steps of: receiving said information about a plurality of available transfer rates if said information is included within said extended information element, in addition to said standardized transfer rate information within said standardized information element, included in said standardized call setup message from said originating exchange unit to said transit exchange unit,   checking whether or not information about each of said plurality of selected rates is available to transfer, taking into consideration free channels of an integrated services digital network (ISDN) trunk line to said terminating exchange unit and discarding information on unavailable transfer rates, and checking whether or not said standardized transfer rate information is available to transfer, and sending a standardized call clearing message to said originating exchange unit if it is unavailable,   sending modified information about a plurality of available transfer rates within said extended information element in addition to said standardized transfer rate information within said standardized information element, included in said standardized call setup message from said originating exchange unit to said terminating exchange unit,   receiving said selected transfer rate information if said information is included within said extended information element included in said standardized call connect message from said terminating exchange unit to said transit exchange unit,   sending said selected transfer rate information within said extended information element if it is received from said terminating exchange unit, or, sending no extended information element, included in said standardized call connect message from said transit exchange unit to said originating exchange unit, and   establishing said ISDN circuit switched connection between said originating exchange unit and said transit exchange unit and between said transit exchange unit and said terminating exchange unit in accordance with said selected transfer rate information if it is included in said standardized call connect message, or in accordance with said standardized call setup message if said extended information element is absent or is invalid in said standardized call connect message, to provide communication between said exchange units.   
     
     
       5. In an exchange equipment in a network in which at least two exchange units are connected between an originating data terminal and a terminating call data terminal, and wherein a call connect message from the terminating call data terminal answers a call setup message from the originating data terminal, to establish communication between said originating data terminal and said terminating call data terminal, an improvement therein comprising: a first exchange unit including a first transfer rate selection means for receiving said call setup message including a plurality of available transfer rates, for provisionally determining said transfer rates which are decided by a free channel in an output circuit for the terminating call data terminal and for sending said transfer rates to said terminating call data terminal; and   a second exchange unit including a second transfer rate selection means for receiving a call connect message from said terminating call data terminal including a transfer rate finally decided by said terminating call data terminal for changing the transfer rate to said finally decided transfer rate, and for mending said changed transfer rate to said originating data terminal, and means for establishing communication, in accordance with said changed transfer rate between said originating data terminal and said terminating call data terminal.   
     
     
       6. An exchange equipment according to claim 5, wherein said first transfer rate selection means includes: means for receiving a call setup message from said originating data terminal including a transfer rate in accordance with the integrated services digital network (ISDN) specification and a plurality of available transfer rates which users can determine freely, for provisionally determining said transfer rates which are determined by a free channel in an output circuit for the terminating call data terminal,   means for sending said transfer rates to said terminating call data terminal, and wherein said second transfer rate selection means includes:   means for receiving a call connect message from said terminating call data terminal including a transfer rate in accordance with the integrated services digital network (ISDN) specification and a transfer rate finally decided by said terminating call data terminal which users can determine freely,   means for changing the transfer rate with said finally determined transfer rate selection means based on said usable transfer rate,   means for sending said changed transfer rate to said originating data terminal.   
     
     
       7. An exchange equipment according to claim 6, wherein said first transfer selection means are configured such that when any of a plurality of transfer rates in the received call setup message is not available in the output circuit for the terminating call data terminal, transfer rates other than the available transfer rate from a plurality of transfer rates within a call setup message are deleted and said call setup message is transmitted to said terminating call data terminal. 
     
     
       8. An exchange equipment according to claim 5, wherein said first transfer selection means are configured such that when any of a plurality of transfer rates in the received call setup message is not available in the output circuit for the terminating call data terminal, transfer rates other than the available transfer rate from a plurality of transfer rates within a call setup message are deleted and said call setup message is transmitted to said terminating call data terminal.